Surface light source device and backlight unit having the same

A surface light source device having LED clusters arranged in a matrix of rows and columns on a board. Each of the LED clusters includes red, green and blue LEDs arranged in a triangle. The LED clusters are grouped into A, E, C and D, which have the red LEDs located top, right, bottom and left, respectively, from a center of the triangle. The matrix of the LED clusters includes alternating first and second type rows arranged repeatedly from top to bottom of the matrix, terminating with the second type row. The first type rows each have first type cluster arrays of the LED clusters arranged in a repeating order of E, C, D and C from left to right. The second type rows each have second type cluster arrays of the LED clusters arranged in a repeating order of A, D, A and D from left to right.